Pot light have been in use for many years, being particularly useful in location having dropped or suspended ceilings, where the pot portion of the installation is readily set into the ceiling, and the wiring provisions are readily arranged and connected above the ceiling.
The usual type of incandescent bulb, with its spherical glass globe is normally accomodated in a pot of some four and a half to six inches in diameter, the pot diameter being such as to permit ready insertion of the hand of an installer through the ceiling aperture, in carrying out the installation.
However, the advent of high intensity halogen light has introduced a number of problems, mainly associated with the high heat concentration associated with these lights, their small size and their low voltage requirements, which require the provision of a step-down transformer.